Question

cos2x+cos10x=0
Пожалуйста помогите

Answer 1

$cos2x+cos10x=0\\ 2cos(frac{2x + 10x}{2})cos(frac{10x - 2x}{2}) = 0\\ cos6xcos4x = 0\\ 1. cos4x = 0\\ boxed{x = frac{pi}{8} + frac{pi n}{4} , z in mathbb{Z}}\\ 2. cos6x = 0\\ boxed{x = frac{pi}{12} + frac{pi n}{6} , z in mathbb{Z}}$